1. Field of the Invention
The present invention relates to the production of multilayer ceramic laminates such as capacitors for electronic application, and more particularly to the production of laminates from a plurality of dielectric ceramic greensheets and interposed conductive electrode layers to form multilayer ceramic laminate units.
The increasing demands for miniaturization and greater electrical capacity of electronic components has created production and performance problems. For example, miniaturization requires the use of thinner insulating ceramic greensheet layers between the conductive layers.
Thin greensheet layers, less than about 3 mils in thickness, are difficult to process into multi-layer ceramic laminates in the conventional production process because the thin greensheets distort greatly and lose mechanical strength during screening with flowable conductive ink or paste composition, and weakened, distorted or warped greensheets are difficult to laminate into reliable multilayer ceramic substrates.
2. Background Art
It is well known to produce multilayer ceramic laminates containing internal capacitors using conventional greensheet technology, and reference is made to U.S. Pat. Nos. 4,868,711; 4,956,744; 5,019,200; 5,046,236; 5,072,329 and 5,304,274 for their disclosures of such laminates and processes for producing them.
In general, the prior known processes include the step of screening flowable conductive metal ink or paste compositions, which may include a ceramic additive, onto dielectric greensheets to form the electrode layers. Therefore such processes encounter the aforementioned distortion and warpage problems if the dielectric greensheets used are less than about 3 mils in thickness.
U.S. Pat. No. 5,072,329 discloses the production of multilayer ceramic capacitive devices in which ceramic metal intervening inks are printed below and above the conductive electrode ink layer printed on a supporting ceramic greensheet layer to form multilayer capacitors in which each printed conductive electrode layer is sandwiched between two printed intervening layers having good bonding properties for both the printed electrode layer on one side thereof and the cast dielectric ceramic layer on the other side thereof. The purpose or function of the printed intervening layer is to provide affinity for both the ceramic greensheet layers and the printed conductive metal layers to resist delamination.